U.S. Pat. No. 6,744,848 (the “'848 patent”), the contents of which are expressly incorporated in its entirety herein, describes a method for creating low-dose three dimensional representations of an object. In summary, the '848 patent discloses that a three dimensional representation of an object can be created using a low radiation dose by creating a three dimensional representation with asymmetric resolution. For example, a useful three dimensional representation of an object can be created that has high resolution in two dimensions and only moderate resolution in the third dimension. If the lower resolution orientation is considered to be the “vertical” direction, then the reconstruction has a high-resolution horizontal plane.
The '848 patent discloses optimized data collection geometries that allow for the efficient acquisition of the data necessary to create the three dimensional representation. In brief, these geometries collect high-resolution data when imaging in a position normal to the high-resolution horizontal plane and lower-resolution data when imaging in a position normal to the lower-resolution vertical direction. The method disclosed in the '848 patent includes rotating a source and a detector about an axis of rotation around an object while maintaining radiation communication therebetween. Images are acquired at a variety of radial positions about the object to enable calculation of a three dimensional representation of the object from two dimensional images.
In practice, it has proven difficult to quickly move detectors and sources from one stationary position to another. In part this is due to the relatively high mass of the radiation source and detector. An inability to quickly move the detector between stations is particularly acute in applications where the total acquisition time must be minimized in order to avoid blurring caused by motion of the object or discomfort to a patient where a portion of the patient's anatomy serves as the object. Mechanical considerations such as residual vibrations have also proven difficult to eliminate when brining the source and detector to a complete stop when acquiring images at various positions.
The present invention is directed toward overcoming one or more of the problems discussed above.